1. Field of the Invention
The present invention relates to a projection type display apparatus.
2. Description of the Related Art
There is a projection type display apparatus known in the related art that executes color separation of light originating from a light source into light of three different colors, irradiates the light having undergone the color separation onto light valves via three polarization beam splitters each provided in correspondence to one of the three colors and uses a composite prism constituted with three triangular prisms as its color composition system (see Japanese Laid Open Patent Publication No. H 10-39771)
The light emitted from the light source is separated into three colors, red (R), green (G) and blue (B), at a cross dichroic mirror constituting the color separation optical system. The optical axis of the light in each of the three different colors resulting from the color separation and exiting the cross dichroic mirror along a specific direction becomes deflected by 90° at a deflecting mirror, and the light in each color becomes substantially parallel light which then advances upward.
The different colors of light each enter the polarization beam splitter provided in correspondence to the color to undergo a polarization split, and the polarized light transmitted through a polarization splitter film enters a reflection type light valve provided in correspondence to the specific color light. The light modulated at the reflection type light valve is then reflected and exits the reflection type light valve to re-enter the polarization beam splitter. The light having entered the polarization beam splitter is analyzed at the polarization beam splitter, and light reflected at the polarization splitter film then enters the color composition optical system. At the color composition optical system, which is constituted with three triangular prisms assuming different shapes, color composition of the different colors of light is achieved. The light having undergone the color composition is projected onto a screen through a projection lens. By adopting the projection type display apparatus structured as described above, the quality of the projected image does not deteriorate since it does not employ a color composition system constituted of a cross dichroic prism in which an adhesive normally present in a cross dichroic prism adversely affects the projected image.